The secretive but brightly-coloured beast, a monitor lizard, is a close cousin of the Komodo Dragon of Indonesia.

Unlike the fearsome Dragon, it is not a carnivore, nor does it feast on rotting meat. Instead, it is entirely peaceable and tucks into fruit.

Dubbed Varanus bitatawa, the lizard measures 6ft 5ins (2m) in length, according to the account, published by Britain's Royal Society.

It was found in a river valley on northern Luzon Island in the Philippines, surviving loss of habitat and hunting by local people who use it for food.

How many of the lizards have survived is unclear.

The species is almost certainly critically endangered, and might well have disappeared entirely without ever being catalogued had a large male specimen not been rescued alive from a hunter last June.

Finding such a distinctive species in a heavily populated, highly deforested location "comes as an unprecedented surprise," note the authors, writing in the journal Biology Letters.

The only finds of comparable importance in recent decades are the Kipunji monkey, which inhabits a tiny range of forest in Tanzania, and the Saola, a forest-dwelling bovine found only in Vietnam and Laos.

The lizard has unique markings and an unusual sexual anatomy, according to the study.

Its scaly body and legs are a blue-black mottled with pale yellow-green dots, while its tail is marked in alternating segments of black and green.

Males have a double penis, called hemipenes, also found in some snakes and other lizards.

The two penises are often used in alternation, and sometimes contain spines or hooks that serve to anchor the male within the female during intercourse.

The lizard has a relative in southern Luzon, V. olivaceous, but the species are separated by three river valleys and a gap of 95 miles (150kms) and may never have met up.

One reason that the new lizard has gone undetected, the researchers speculate, is that it never leaves the forests of its native Sierra Madre mountains to traverse open spaces.